1. Field of the Invention
This invention relates in general to the structure and fabrication method of a diode color sensor, and more particularly to the structure of a type of Complementary Metal-Oxide-Semiconductor (CMOS) diode color sensor by using a black matrix layer.
2. Description of Related Art
CMOS diodes are usually used in the a PC Camera and digital camera. In general, the structure of a diode color sensor is that there is a color sensor layer, which includes many different color sensor areas corresponding to different colors, on the substrate. Then, this color sensor layer is covered by a color filter which is further protected by a cover film. Incident light, usually including all possible kinds of colors and incident angles, will be filtered into three types of color light, such as red light, green light and blue light, while it is filtered by the color filter. Each color light is then absorbed and sensed by the respective color sensor.
The structure of a conventional CMOS diode is shown in FIG. 1, which includes a color sensor layer 12 deposited on a substrate 10. The color sensor layer 12 includes different color sensor areas, 12a, 12b, and 12c. Then, a color filter 14 is formed on the top of the color sensor layer 12, that is, the color sensor areas 12a, 12b, and 12c. The color filter 14 protected by a cover film 16 is composed of a red filter R1, a green filter G1 and a blue filter B1 corresponding to color sensor areas 12a, 12b, and 12c, respectively. The incident light, usually including all possible kinds of colors and incident angles, will be filtered into three types of color light, such as red light, green light and blue light, while it is filtered by the color filter. Each color light is then absorbed and sensed by the respective color sensor.
The conventional diode color sensor as described above has a lot of problems as follows:
1. When the incident light is filtered through the color filter, because of the scattering effects occurring at color filters. Color quality of each monochromatic light is deteriorated. PA0 2. Because the present technique on the CMOS diode has achieved a level of high resolution of pixels with an order of million, a pixel size is as small as 5 .mu.m causing the light excited rate being decreased and a planarization film being needed either, these result in the more requirement of the light receiving performance for the monochromatic light of red, green and blue. PA0 3. Conventionally, the color sensor layer has no effective light shielding means. Typically existing metal lines on the wafer are used as a means for light shielding. However, this kind of light shielding means is ineffective due to its position being not located right above the color sensor layer and its large scale of light shielding and more that the cost is tremendously increased due to extra process steps and photo-mask being required.